1. Field
The following description relates to an optical communication system, and more particularly to a wavelength selection and configuration method for multi-wavelength optical communication system.
2. Description of the Related Art
Optical access network technologies actively under discussion may be divided into Time Division Multiplexing Passive Optical Network (TDM-PON) technology and Wavelength Division Multiplexing Passive Optical Network (WDM-PON) technology. The Time Division Multiplexing Passive Optical Network (TDM-PON) has a structure in which an Optical Line Termination (OLT) and a plurality of Optical Network Units (ONUs) are connected through a passive optical power splitter, and a single transmission wavelength is shared by a plurality of Optical Network Units (ONUs) in an optical layer. In the Time Division Multiplexing Passive Optical Network (TDM-PON), downstream data transmission is performed by a time division multiplexing scheme and upstream data transmission is performed by a Time Division Multiple Access (TDMA) scheme.
In the Wavelength Division Multiplexing Passive Optical Network (WDM-PON), an Optical Line Termination (OLT) and a plurality of Optical Network Units (ONUs) are connected through a passive optical wavelength splitter, and the plurality of Optical Network Units (ONUs) are connected to the OLT using a plurality of wavelengths allocated separately to each ONU. In the Wavelength Division Multiplexing Passive Optical Network (WDM-PON), upstream and downstream data transmission is performed by a wavelength division multiplexing scheme.
In the conventional optical network technology, a predetermined wavelength is used.
That is, in the conventional optical network system, regardless of a quantity of usage bandwidth, all wavelength channels are used all the time from installation. For example, in the Time-division multiplexing Passive optical network (TDM-PON), upstream and downstream data transmissions each use one wavelength, while in the Wavelength-division multiplexing Passive optical network (WDM-PON), upstream and downstream data transmissions have been performed through a plurality of channels using optical wavelengths predetermined for each channel, always using all wavelengths allocated for each channel regardless of actual usage bandwidth.
However, in a future optical communication system, it will be necessary to change the number of used channels according to a bandwidth to be used. Accordingly, the number of used channels should be changed such that fewer channels are used when the bandwidth is narrow, and more channels are used when the bandwidth increases.
For example, in an optical network, one channel is used in an initial stage depending on a number of subscribers, and thereafter, a second channel is used when the scale exceeds the certain number of subscribers. Accordingly, in an optical communication system, energy consumption can be reduced by preventing channels from being unnecessarily used and using bandwidth effectively. Especially, in the TDM-PON, a receiver should satisfy a characteristic of receiving upstream signals in a burst mode, so bandwidth cannot be increased easily. Therefore, it is advantageous to use a plurality of wavelengths for increasing bandwidth for upstream signals and it is required to increase upstream bandwidth according to demand when increasing bandwidth using a plurality of wavelengths.